Hidden colonic adenomas in a patient with a family history of polyposis

We describe an asymptomatic patient with a strong family history of polyposis who was found to have flat and depressed adenomas that were not visible on colonoscopy. The diagnosis required assessment of multiple, randomly obtained biopsy specimens. Partial deflation of the colon during colonoscopy may allow hidden lesions to be seen. Biopsies should be performed in all patients with a family history of polyposis who are examined colonoscopically, even if they are asymptomatic and no lesions are visible through the colonoscope.